Intravenous metering device

ABSTRACT

An intravenous metering device is provided which includes an air retention chamber in downstream fluid communication with a source of fluid and in upstream fluid communication with a pumping chamber. A first valve is provided between the air retention chamber and the pumping chamber to control access to the pumping chamber. A second valve is provided to control the exit of fluid from the pumping chamber. The valves include a shared diaphragm portion. A safety mechanism as provided to prevent accidental free flow of fluid through the metering device. In a first preferred embodiment of a safety mechanism, a gradually tapered priming stem is provided attached to the diaphragm portion of the second valve. In a second preferred embodiment of a safety mechanism, a priming stem is provided attached to the diaphragm portion of the second valve and a priming stem release mechanism is further provided.

CROSS REFERENCE

The present invention is a continuation-in-part of U.S. Pat. ApplicationSer. No. 411,789 filed 25 Sept. 1989, now U.S. Pat. No. 5,108,373.

FIELD OF THE INVENTION

The present invention relates in general to intravenous metering devicesand in particular to an intravenous metering device utilizing animproved check valve.

BACKGROUND OF THE INVENTION

Considerable attention in recent years has been directed to theintravenous delivery of fluids such as saline solutions and the like topatients. Initially, these fluids were administered to the patient bymeans of gravity flow from a container holding the fluid to bedelivered. Gravity-flow devices, however, can be cumbersome to use,inasmuch as pressure sufficient to sustain fluid movement in agravity-flow device often required positioning of the device at aconsiderable elevation above the patient receiving the fluid. Moreover,attempts to accurately regulate the amount of fluid administered bygravity-flow devices were often unsuccessful because of the fact thatthe gravity-induced pressure responsible for moving fluid through thedevice generally decreased during the intravenous delivery operation asthe fluid level within the container holding the fluid dropped.

In order to provide for improved flow of fluids to patients, pumpingdevices have been utilized, such as found in U.S. Pat. Nos. 4,336,800;4,453,931; 4,453,932; and 4,457,713. Such pumping devices employ ametering device control unit into which an intravenous metering deviceis placed. The intravenous metering device includes a pumping chamberwhich includes a reciprocal diaphragm. The metering device includes apumping piston which reciprocates the diaphragm thereby changing thevolume of the pumping chamber. Check valves are positioned at thepumping chamber inlet and outlet to regulate the flow of fluid and a gasretention chamber is provided upstream of the pumping chamber and thepumping chamber inlet. The gas retention chamber is connected via tubingto a fluid source while the pumping chamber outlet is connected to apatient.

The intravenous metering devices found in these patents all employcomplex structure including a biased ball check valve. While such checkvalve performs adequately, the multiplicity of moving parts isundesirable due to cost factors and the variation in functionalityassociated with manufacturing complexity. What is thus needed is anintravenous metering device which improves on the use of such biasedball check valve.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an intravenous metering device whichincludes a pumping chamber and means for varying the volume of thepumping chamber. In a preferred embodiment, the pumping chamber includesa reciprocating diaphragm with the volume varying means reciprocatingthe diaphragm to provide the pumping action. The pumping chamberincludes an inlet having a first valve to control the entry of fluidinto the fluid pumping chamber and an outlet with a second valve tocontrol the exit of fluid from the pumping chamber. An air retentionchamber is also provided upstream of the pumping chamber to ensure thatthe fluid entering the pumping chamber is free of air bubbles. The airretention chamber is in fluid communication with a source of fluid whilethe outlet of the pumping chamber is connected to a patient.

The first valve includes a flexible diaphragm which in a relaxedposition opens the inlet and in a stressed position closes the inlet.The second valve includes a diaphragm which is normally in a closedposition but which can be stressed into an open position. A safety meansis further provided which prevents accidental free flow of the meteredfluid. Thus, the present invention provides an intravenous meteringdevice which improves on the intravenous metering devices of the priorart.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the use of an intravenousmetering device in accord with the principles of the present invention;

FIG. 2 is a top view showing an intravenous metering device in accordwith the principles of the present invention;

FIG. 3 is a cross-sectional view of the device of FIG. 2 taken alongline III--111 of FIG. 2;

FIG. 4 is a cross-sectional view of the device of FIG. 2 taken alongline IV--IV of FIG. 2;

FIG. 5 is a cross-sectional view of the device of FIG. 2 along line V--Vof FIG. 2;

FIG. 6A is an upper perspective view of the diaphragm device of thepresent invention;

FIG. 6B is a lower perspective view of the diaphragm device of thepresent invention;

FIG. 7A is a view similar to FIG. 2 showing an alternative embodiment ofan intravenous metering device in accordance with the principles of thepresent invention;

FIG. 7B is a view of the device of FIG. 7A, similar to the view of FIG.5; and

FIG. 8A-8D are views similar to FIG. 5 showing an alternative embodimentof an intravenous metering device in accordance with the principles ofthe present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring first to FIG. 1, an intravenous metering device 10 is shownpositioned within a metering device control unit 12. The intravenousmetering device 10 in conjunction with the metering device control unit12 acts as a pump means to transfer fluid from a source of fluid 14 to apatient. The intravenous metering device 10 is connected to the sourceof fluid 14 by means of conventional tubing 16. Additional tubing 18,extending from the outlet of intravenous metering device 10, transfersprecise amounts of fluid to the patient.

Provided between the container of fluid 14 and the tubing 16 is aconventional drip chamber 15. The drip chamber 15 is partiallysurrounded by a drop sensing means 17 which senses the drops passing inthe drip chamber 15. The drop sensing means 17 is connected to themetering device control unit 12 by wiring 13 so that, if the absence ofdrops is sensed, an alarm in the metering device control unit 12 can besounded.

Referring now to FIGS. 2 thru 5, construction of an intravenous meteringdevice 10 in accord with the principles of the present invention isshown in detail. The intravenous metering device 10 includes a pumpingchamber 20 formed in housing 30 and a flexible diaphragm 22 which formsan upper portion 21 of pumping chamber 20. The housing 30 includes ahousing lid 31 as well as a housing bottom 32. A pumping chamber inlet24 and a pumping chamber outlet 26 are formed in pumping chamber 20.Pumping chamber 24 includes a valve seat means 28. Valve actuator 34controls the admission of fluid into pumping chamber 20 by reciprocatingthe diaphragm 22 between an open position, shown in solid lines in FIG.3, and a closed position as shown by dotted lines in FIG. 3. As bestseen in FIG. 4, the pumping chamber outlet 26 includes a valve 38 whichis normally held in a closed position.

Intravenous metering device 10 further includes a metering device inlet49 which is disposed above an air retention chamber 40 bounded byhousing sidewalls 42. The air retention chamber 40 is of sufficient sizeto include an air retention chamber upper portion 50 providing for anair-fluid interface. Air retention chamber 40 also includes an airretention chamber lower portion 54 which collects fluid free of airbubbles. The fluid free of air bubbles can then pass through an airretention chamber passageway 56 in tubular conduit 58 past the openvalve seat means 28 and on into the pumping chamber 20.

The metering device control unit 12 provides means for varying thevolume of the pumping chamber 20 in order to pressurize the Pumpingchamber 20 to provide fluid propulsion. These means can include meansfor flexing diaphragm 22 into pumping chamber 20 which in the presentinvention is a reciprocating pumping piston 60 which presses againstflexible diaphragm 22, whereupon fluid free of air bubbles is pumpedthrough the intravenous metering device 10 as described below. Theposition of diaphragm 22 shown by solid lines in FIG. 3 illustrates thecondition of the diaphragm 22 when pumping piston 60 is in the upstrokeposition while the dotted line position of diaphragm 22 illustrates theposition of the diaphragm 22 in the associated down-stroke position ofpumping piston 60.

It is important to measure the pressure of fluid downstream or distal ofthe intravenous metering device 10. Excessive distal pressure mayindicate a plugged filter or distal line occlusion. Accordingly, theintravenous metering device 10 of the present invention includes apressure indicating means for determining distal pressure. This pressureindicating means includes a pressure measuring chamber seen in FIG. 5.

The distal pressure measuring chamber itself is incorporated into thefluid flow path leaving the pumping chamber 20 so that priming will beaccomplished in generally the same manner as with the pumping chamber20. Intravenous metering device 10 is constructed with a distal pressuremeasuring chamber 70 and an intravenous metering device outlet 72positioned at the base of distal pressure measuring chamber 70. Anintermediate passageway 74 is formed to carry fluid from the pumpingchamber outlet 26 past valve 38 into the distal pressure measuringchamber 70 entering at a distal pressure inlet 78. The intravenousdevice outlet 72 is located at the bottom of distal pressure measuringchamber 70 so that the distal pressure measuring chamber 70 is made apart of the fluid flow path through intravenous metering device 10. Theflow of the fluid during the intravenous metering device 10 primingoperation described below will continue on into the distal pressuremeasuring chamber 70, removing air otherwise present in the intravenousmetering device 10 from the distal pressure measuring chamber 70 as wellas the pumping chamber 20.

Distal pressure pin 82 is oriented over a portion 80 of diaphragm 22which covers the distal pressure measuring chamber 70 as shown, andmovement of distal pressure pin 82 in response to upward motion ofdiaphragm portion 80 can be translated into a distal pressure reading byemploying a measuring device which measures the movement of distalpressure pin 82. Also, as seen in FIG. 4, the snifting of theintravenous metering device elements in order to incorporate the distalpressure measuring chamber 70 results in the placement of valve 38 at alocation somewhat remote from pumping chamber 20. An elongatedpassageway 90 is therefore formed in the intravenous metering device 10to transport fluid from the pumping chamber 20 to the valve 38.

Referring to FIGS. 6A and 6B, a perspective view of the diaphragm 22 isseen in detail, both from above and below. The diaphragm 22 includes theupper portion 21 of pumping chamber 20 which is reciprocable by pumpingpiston 60 to vary the volume of the pumping chamber 20. The diaphragm 22also includes the upper portion 80 of the distal pressure measuringchamber 70. This portion 80 of the diaphragm 22 includes a generallyfunnel shaped aperture 81 into which distal pressure pin 82 is held.

Diaphragm 22 further includes valve seat means 28 which, in conjunctionwith housing 30, forms pumping chamber inlet 24. Valve seat means 28 isreciprocable by valve activator 34 to control admission of fluid intopumping chamber 20.

Extending upwardly from the diaphragm 22 is the integrally formedpriming stem 110. The priming stem 100 includes an increased diameterportion 111 and a stem base 113. The junction of the increased diameterportion 111 and stem base 113 defines a stem flange 115. The primingstem 110 further includes a grip portion 117 to aid in user gripping. Onthe diaphragm opposite the primary stem is standpipe contacting portion119 which establishes contact with standpipe 98.

Extending downwardly from the diaphragm 22 is an integrally formedflapper valve 110 which forms with a molded ramp 102 on housing 30 aone-way valve. This one-way valve separates the intermediate passageway74 from the distal pressure measuring chamber 70. Also extendingdownwardly is a biasing ridge 79 which acts to bias flapper valve 100against molded ramp, as seen in FIG. 5.

Referring back to FIGS. 2-5, operation of the device will be described.When pressure is applied to the pumping chamber 20 by the pumping piston60, the fluid flows from the pumping chamber 20 through the pumpingchamber outlet to the elongated passageway 90. An annular outletpressure chamber 96 is formed at the downstream end of elongatedpassageway 90 having as its upper wall the diaphragm 22. A standpipe 98having an aperture 99 defined along its central axis is centered inoutlet pressure chamber 96. At its upper periphery, the standpipe 98 ispre-loaded against the diaphragm 22 thus forming a fluid seal to preventfluid flow.

When sufficient pressure is generated in pumping chamber 20 and outletpressure chamber 96, the diaphragm 22 is lifted off the standpipe 98thus opening valve 38. With valve 38 open, fluid passes into theintermediate passageway 74. Because air is compressed more readily thanfluid, if air is trapped in the pumping chamber 20, sufficient pressurewill not be generated in the pumping chamber 20 and outlet pressurechamber 96 to lift the diaphragm 22 off the standpipe 98. This disablesthe intravenous metering device 10 which acts as a safety means toprevent air from being pumped downstream to the patient.

From the intermediate passageway 74, the fluid enters the distalpressure measuring chamber 70. Provided at the opening to the distalpressure measuring chamber 70 is a one-way flapper valve 100 carried ona molded ramp 102 formed integrally as part of cassette housing 30. Theflapper valve 100 is integrally molded as part of diaphragm 22 to bebiased against the molded ramp 102. The flapper valve 100 thus acts as avalve to allow fluid to pass into the distal pressure measuring chamber70 but to prevent fluid from flowing back into the intermediatepassageway 74 and back to the pumping chamber 20. Also extendingdownwardly is a biasing ridge 79 which acts to bias flapper valve 100against molded ramp 102, as seen in FIG. 5.

The diaphragm 22 further includes an integrally molded priming stem 110extending from the diaphragm 22 above the outlet valve 38 portion. Thepriming stem 110 includes an upper increased diameter portion 111integrally formed with a stem base 113 thereby defining a stem flange115. The priming stem 110 can be pulled to manually lift the diaphragm22 off the standpipe 98 to open the pumping chamber outlet 26. Inaddition, formed in the housing lid surrounding the priming stem 110 isstem lock housing 112. The stem lock housing 112 includes a stem lockinggroove 114, best seen in FIG. 5, in which the stem flange can rest.Also, as best seen in FIG. 2, the stem lock housing 112 is generallyformed as an arrow to direct the user to the stem locking groove 114.

Prior to use, the intravenous metering device must be primed toeliminate air from the device. When intravenous metering device 10 is tobe primed, the device is inverted, and the priming stem 110 is pulledsuch that the diaphragm 22 is lifted off the standpipe 98 to open thepumping chamber outlet 26 so as to allow the sequential passage of fluidfrom metering device inlet 49 through the air retention chamber 40 andthe pumping chamber 20 to the distal pressure measuring chamber 70 tothe outlet tubing 18. With the device inverted each of the chambers 20and 40 are primed by directing the fluid into the bottom and allowingthe fluid to fill the chambers upwardly. Such relatively constant fluidflow assures the elimination of air prior to use of the intravenousmetering device 10, consequently enabling the intravenous meteringdevice 10 to administer fluid free of air bubbles to a patient.

Following the priming operation, intravenous metering device 10 isreturned to its upright position and inserted into metering devicecontrol unit 12. Incoming fluid, transmitted by tubing 16 to theintravenous metering device inlet 49, subsequently passes into the airretention chamber 40 which, due to the downward extension of tubularconduit 58, prevents any air from entering the pumping chamber 20 andallows for the generation of a air-fluid interface in air retentionchamber upper portion 50. Fluid free of air bubbles passes from the airretention chamber lower portion 54 through passageway 56. When valveactuator 34 is reciprocated upwardly, fluid free of air bubbles isallowed to pass into pumping chamber 20. Valve actuator 34 is thenclosed. As the flexible diaphragm 22 is moved downwardly by means of thepumping piston 60, the volume within pumping chamber 20 is decreased andthe pressure within pumping chamber 20 and outlet pressure chamber 96lifts the diaphragm 22 off the standpipe 98, thereby allowing a preciseamount of metered fluid to be pumped from pumping chamber 20 through theintravenous metering device outlet 72 to a patient. The intravenousmetering device 10 of the present invention may be disposable,permitting a fresh and sterilized intravenous metering device 10 to beemployed for each delivery of intravenous fluid to a patient.

It has been found that, in certain instances, it is advantageous toassure the diaphragm 22 is abutted against the standpipe 98 prior toinsertion of the intravenous metering device 10 into metering devicecontrol unit 12. To this end, safety means are provided for directingthe diaphragm against the standpipe. While such means can be manuallyoverridden to prime the intravenous metering device 10 in theaforementioned manner, such means assures that after insertion into theintravenous metering device control unit 12, a free flow of fluidthrough the metering device, known as a free flow condition is notpresent.

Referring now to FIGS. 7 and 8, two embodiments of such safety means fordirecting the diaphragm against the standpipe are seen. Referring firstto FIG. 7, a preferred embodiment of the present invention having safetymeans for directing the diaphragm against the standpipe is seen. In thisfirst preferred embodiment, these means included a priming stem 110having an upper increased diameter portion 111 integrally formed with astem base 113. However, in this preferred embodiment, the integralformation of the upper increased diameter portion 11 and the stem baseincludes a gradually tapered area 120 rather than stem flange, best seenin FIG. 7B.

The upper portion 21 of the pumping chamber 20 forms a housing lid bestseen in FIG. 7A. In this first preferred embodiment, the housingsurrounding the priming stem 110 includes a constant width funnel shapedmember 122.

To prime, the priming item 110 can be pulled to manually lift thediaphragm 22 of the standpipe 98 to open the pumping chamber outlet 26.However, in this embodiment, upon release of the manual intervention,the diaphragm is directed against the standpipe so that a free flowcondition cannot occur without normal intervention.

Referring now to FIG. 8, a second preferred embodiment of safety meansfor directing the diaphragm against the standpipe is seen. In thissecond embodiment, the primary stem 110 includes an upper increaseddiameter portion 111 integrally formed with a stem base 113 therebydefining a stem flange 115. The stem lock housing 112 includes a stemlocking groove 114. Thus, when the priming stem 110 is manually pulledto lift the diaphragm 22 off the standpipe 98, the stem flange 115 canrest in the stem locking groove 114.

This second preferred embodiment further includes a priming stem releasemechanism 126. The priming stem release mechanism 126 includes a collar128 which is adapted to be secured around the stem lock housing 112.Pivotally contained extending from the collar 128 is a generally bentmember 130 which includes a lower arm segment 132 and an upper armsegment 134 joined at an elbow 136. The plane of the lower arm segment132 at rest extends upwardly from the plane of the collar at an angle ofabout 25°. The plane of the upper arm member 134 extends from the planeof the lower arm member 132 at an angle of about 100°. Thus, at the restportion, the release mechanism does not interfere with the manualpriming operation of pulling and resting the primary stem 110 in thestem locking groove 114.

However, if the intravenous metering device 10 is loaded into theintravenous metering device control unit 12 while the priming stem 110is in the stem locking groove 114, the release mechanism 126 acts toforce the priming stem out of the stem locking groove 114 thus directingthe diaphragm 22 into contact with the standpipe 98. This resultsbecause the upper arm member 134 contacts the splash shield of thehousing of the intravenous metering device control unit 12 which pivotsthe release mechanism 126 member, which causes the lower arm member 132to contact against and force the priming stem 110 out of the stemlocking groove 114.

It should be understood that various changes and modifications to thepreferred embodiments described herein will be apparent to those skilledin the art. Such changes and modifications can be made without departingfrom the spirit and scope of the present invention without diminishingits attendant advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

What is claimed is:
 1. A device which meters fluid for delivery from asource of fluid to a patient, comprising:an air retention chamber havingupper and lower portions, the upper portion having an inlet in fluidcommunication with the source of fluid, the lower portion having anoutlet in fluid communication with a fluid passageway; a pumping chamberhaving an inlet and an outlet, the inlet being in fluid communicationwith the fluid passageway, the pumping chamber inlet including a firstvalve to control the entry of fluid into the pumping chamber, thepumping chamber outlet including a second valve having an outletpressure chamber in fluid communication with the pumping chamber andhaving a diaphragm as an upper wall; a standpipe prestressed against thediaphragm; means for varying the volume of the pumping chamber topressurize the pumping chamber, the diaphragm being capable of openingin response to an increase in the pumping chamber pressure; and safetymeans for preventing accidental free flow of fluid through the meteringdevice.
 2. A device which meters fluids for delivery from a source offluid to a patient, comprising:an air retention chamber having upper andlower portions, the upper portion having an inlet in fluid communicationwith the source of fluid, the lower portion having an outlet in fluidcommunication with a fluid passageway; a pumping chamber having an inletand an outlet, the inlet being in fluid communication with the fluidpassageway, the pumping chamber inlet including a first valve to controlthe entry of fluid into the pumping chamber; the pumping chamber outletincluding a second valve including a normally closed flexible diaphragmportion; means for varying the volume of the pumping chamber topressurize the pumping chamber, the normally closed diaphragm beingcapable of opening in response to an increase in the pumping chamberpressure; and safety means for preventing accidental free flow of fluidthrough the metering device, the safety means comprising a graduallytapered priming stem attached to the flexible diaphragm portion of thesecond valve.
 3. A device which meters fluid for delivery from a sourceof fluid to a patient, comprising:an air retention chamber having upperand lower portions, the upper portion having an inlet in fluidcommunication with the source of fluid, the lower portion having anoutlet in fluid communication with a fluid passageway; a pumping chamberhaving an inlet and an outlet, the inlet being in fluid communicationwith the fluid passageway, the pumping chamber inlet including a firstvalve to control the entry of fluid into the pumping chamber, thepumping chamber outlet including a second valve including a normallyclosed flexible diaphragm portion; means for varying the volume of thepumping chamber, the normally closed diaphragm being capable of openingin response to an increase in the pumping chamber pressure; and safetymeans for preventing accidental free flow of fluid through the meteringdevice, the safety means comprising a priming stem attached to theflexible diaphragm portion of the second valve means for securing, thepriming stem in a free flow condition, and a priming stem release meansfor assuring release of the priming stem to return the flexiblediaphragm portion of the second valve to the normally closed position.